The use of gel-forming solutions for preparing glasses and glass-ceramics

Abstract

Solutions composed of hydrolyzed TEOS, orthophosphoric acid and nitrates were prepared. An increase of the solution temperature accelerates the sol-gel transition. The gel formation starts at 60–650°C for Si-containing solutions and at 35–40°C for SiP solution. The molten glass of composition (mass%) 41.9SiO 2·51ZnO·7.1K 2O (s-glass) was obtained from solid residue precipitated from the solution. The EM-study of the microstructure of this glass and the charge-formed f-glass of similar composition showed that at 800°C the s-glass starts to crystallize with a delay compared to the f-glass. The phase transformations of both the glasses are analogous in nature and sequence of phase formation. For glass-ceramics, the interaction at the interface: oxide filler-glass binder from the solution was studied. The glass formation within the cake volume sometimes hinders the interaction of the filler with the glass binder components. The solutions can be used in ceramic suspensions to produce thin-layer flexible coatings at temperatures not higher than 800°C.